1. Field of the Invention
The present invention relates to a method and an apparatus for connecting an electronic component suitable for use in the case where an electronic component such as a liquid crystal display device having a plurality of connecting terminals juxtaposed with each other at a small pitch is connected to a printed circuit board via an anisotropically conductive sheet by compression bonding.
2. Description of the Related Art
Recently, a liquid crystal display device has come to be widely used as one of the display devices. Making use of their features of being small in thickness and consuming low power, the liquid crystal display devices have been used in watches and electronic calculators and lately, their use mounted on an IC card has been considered.
In connecting a liquid crystal display device to a printed circuit board, there are frequently cases where contact points amounting to 80 or so in number, at a pitch of about 0.4 mm, have to be connected. In such a case, it is very difficult to achieve the connections by ordinary soldering. Therefore, as shown in FIG. 1, such a method as to have an anisotropically conductive sheet 9 sandwiched in-between connecting terminals of the liquid crystal display device 1 and wiring patterns 7 formed on the printed circuit board 5 and connect a pile of these members together by thermal compression bonding. It should be understood that the anisotropically conductive sheet is a sheet having conductivity only in one direction, while having electrical insulating property in all the other directions. A conventional method for such connection is described, for example, in U.S. Pat. No. 4,261,042.
However, when the compression bonding conditions of the wiring patterns 7 are investigated, it is found that the outermost wiring patterns 7A, 7B of the wiring patterns 7 are liable to be subjected to uneven abutting force via the anisotropically conductive sheet 9 as compared with the abutting force on other wiring patterns 7 via the same due to the fact that there are absent any adjoining wiring patterns on their outer sides (on the left-hand side and right-hand side of the outermost wiring patterns 7A, 7B in the figure). As a result, there has been the possibility that electrical conductivities at these connections become insufficient.